In late February, a large portion of the Arctic Ocean near the North Pole experienced an alarming string of extremely warm winter days, with the surface temperature exceeding 25 degrees Fahrenheit above normal.
These conditions capped nearly three months of unusually warm weather in a region that has seen temperatures rising over the past century as greenhouse gas concentrations (mostly carbon dioxide and methane) have increased in the atmosphere. At the same time, the extent of frozen seawater floating in the Arctic Ocean reached new lows in January and February in 40 years of satellite monitoring.
In recent years, the air at the Arctic Ocean surface during winter has warmed by over 5 degrees Fahrenheit above normal. So was this recent spate of warm weather linked to longer-term climate change, or was it, well, just the weather?
What we can say is this: Weather patterns that generate extreme warm Arctic days are now occurring in combination with a warming climate, which makes extremes more likely and more severe. What’s more, these extreme temperatures have had a profound influence on sea ice, which has become thinner and smaller in extent, enabling ships to venture more often and deeper into the Arctic.
This sea ice loss, in turn, has created a feedback loop. Thinner, receding ice allows the ocean’s heat to escape more readily into the atmosphere, which the Arctic’s highly stable lower atmosphere traps near the surface during the polar night. As a result, winter surface air temperatures have warmed more in the Arctic compared with the global average.
